TekVet System spots unhealthy animals by monitoring their body temperature using a small wireless device attached to the animal’s ear. When the body temperature drops below or climbs above specific temperature guidelines, producers are notified electronically about the change, so that they can treat sick animals and return them to full health more quickly.

By reaching sick animals more promptly, the cost of caring for them is lowered, and the average profit per animal rises accordingly.
Oh! I thought it was just for the love of animals, how can I be so naive?

Via Using RFID.